Water-in-oil emulsion explosive containing entrapped gas

ABSTRACT

A water-in-oil emulsion explosive composition comprising a carbonaceous fuel, an inorganic oxidizer, a detonation sensitizer, water, an emulsifier, and a gas. The detonation catalyst is an inorganic metal compound of atomic number 13 or greater, other than Groups Ia and IIa and other than dioxides. The detonation sensitizer greatly enhances the sensitivity of the compositions so that they are cap-sensitive, the preferred compositions being cap-sensitive in a 1-inch diameter cartridge.

United States Patent Wade 1 51 Feb. 6, 1973 1 1 WATER-IN-OIL EMULSION 3,113,060 12/1963 Cooley ..149/47 EXPLOSIVE CONTAINING 3,161,551 12/1964 Egly et a1 ....149 47 x ENTRAPPED GAS 3,2 I 2,945 lO/l965 Berthmann et al. ..l49/47 3,356,547 12/1967 Berthmann et al. "149/47 x Primary Examiner-Benjamin R. Padgett Assistant Examiner-Stephen J. Lechert, Jr. Att0rneyKenneth E. Mulford and Roger R, Horton [57] ABSTRACT A water-in-oil emulsion explosive composition comprising a carbonaceous fuel, an inorganic oxidizer, a detonation scnsitizer water, an emulsifier, and a gas. The detonation catalyst is an inorganic metal compound of atomic number 13 or greater, other than Groups la and lla and other than dioxides. The detonation sensitizer greatly enhances the sensitivity of the compositions so that they are cap-sensitive, the preferred compositions being cap-sensitive in a 1-inch diameter cartridge.

16 Claims, N0 Drawings WATER-IN-OIL EMULSION EXPLOSIVE CONTAINING ENTRAPPED GAS This invention relates to a water-in-oil emulsion explosive composition containing a detonation sensitizer.

Bluhm U.S. Pat. No. 3,447,978 discloses ammonium nitrate blasting compositions in the form of water-in-oil emulsions. While the compositions described in that patent have many advantages over conventional slurry blasting compositions, they are typically not cap-sensitive. Therefore, it is necessary to employ a booster in order to detonate them.

It has now been found that waterin-oil emulsion explosive compositions can be prepared which retain all of the advantages of the emulsion blasting agents described in the Bluhm patent but which, in addition, are cap-sensitive without the use of an explosive ingredient, the preferred compositions being cap-sensitive in diameters of 1 inch or even less, and this sensitivity is maintained at low temperatures (less than 20 F.) and over extended storage periods (at least three months). Thus, it is not necessary to employ a booster to detonate the compositions of this invention. The compositions of this invention have excellent water resistance and safety characteristics in that they have high resistance to burning, impact, friction, rifle bullets, and static. They do not cause headaches, as do compositions employing nitroglycerin, and they have unexpectedly high velocities (typically, 17,000 ft./sec.) in l-inch diameters and unexpectedly high detonation pressures (typically, 90 to 1 l kilobars).

Moreover, the greatly enhanced sensitivity of the compositions of this invention was brought about without the addition of any ingredient which is cap-sensitive in itself. The detonation sensitizers which are responsible for the increased sensitivity of the compositions of this invention need not be explosive at all, and, in fact, it is really quite amazing that such explosively inert compounds as copper chloride and iron oxide would function to increase the sensitivity of an emulsion explosive.

The cap-sensitive compositions of this invention comprise about 1 to about percent (all percentages herein are by weight) carbonaceous fuel, about 55 to about 87 percent oxidizer, about 0.1 to about percent detonation sensitizer, about 10 to about percent water, about one-half to about 2 percent emulsifier, and sufficient gas to give the composition a density of about 0.9 to about 1.40 gms./cc. The preferred compositions which are cap-sensitive in l-inch diameters comprise about 2 to about 6 percent carbonaceous fuel, about 75 to about 85 percent oxidizer, about 2 to about 6 percent detonation sensitizer, about 15 to about 20 percent water, about three-fourths to l A percent emulsifier, and sufficient gas to give the composition a density of about 1.05 to about 1.25 gms./cc.

The compositions preferably contain a gelling agent which greatly increases storage stability. The preferred amount of gelling agent is about 0.25 to about 2.0 percent. Examples of suitable gelling agents include polyacrylamide, interpolymers of methyl vinyl ether and maleic anhydride and their salts, guar gum, etc.; guar gum is preferred.

The compositions may also contain up to about 10 percent auxiliary fuel, such as sulfur, sugar, urea, formamide, dimethyl formamide, carbon, aluminum, or

magnesium, preferably aluminum, aluminum alloys, or

sulfur for greatest sensitivity. Up to about one-third of the water may be replaced with a water-soluble fuel such as ethylene glycol, low molecular-weight alcohols 5 such as methanol, ethanol, or propanol; however, water is preferred because of its economy and because it is a better solvent for the oxidizing salts. Other optional ingredients include glycerine, formamide, dimethyl formamide, sugar, and water-soluble alkylamines such as ethylene diamine and methylamine.

The carbonaceous fuel is a water-immiscible, emulsifiable fuel which is liquifiable at a temperature up to about 200 F. and preferably between about 110 F. and about 160 F. to facilitate aeration and packaging. Waxes having melting points of at least 80 F. and preferably in the range of about 1 10 F. to about 200 F. are usually suitable; examples include waxes derived from petroleums such as petrolatum wax, microcrystalline wax, and paraffin wax, mineral waxes such as ozocerite and montan wax, animal waxes such as spermacetic wax, and insect waxes such as beeswax and Chinese wax. A modified, highly cohesive microcrystalline wax having a melting point of about 1 l4-1 1 9 F. and identified by the trademark Indra 21 19" sold by Industrial Raw Materials Corp. and a similar wax sold by the same company under the trademark Indra 1153 having a melting point of about 150l55 F. are preferred as they give good sensitivity and stability.

While greatest sensitivity is achieved if the carbonaceous fuel is 100 percent wax and this is preferred, up to about 60 percent of the wax may be replaced with an oil to increase long-term storage stability. Examples of suitable oils include the various petroleum oils, DNT, and various vegetable oils; a highly refined mineral oil sold by Atlantic Refining Co. under the trademark Atreol 34 is preferred if an oil is used as it gives good stability.

The oxidizer may be about 20 to about 95 percent ammonium nitrate (AN), about 5 to about 40 percent other inorganic nitrate, up to about 60 percent ethylene diamine dinitrate (EDDN), up to about 40 percent alkylamine nitrate or alkanolamine nitrate, and up to about percent inorganic chlorate or inorganic perchlorate. The oxidizer which is preferred for greatest sensitivity comprises about 55 to about 80 percent (AN), about 5 to about 15 percent sodium nitrate (SN), about 10 to about 20percent EDDN, and about 5 to about 10 percent ammonium perchlorate (AP). Examples of suitable other inorganic nitrates include sodium nitrate, which is preferred for greatest sensitivity, potassium nitrate, lithium nitrate, calcium nitrate, magnesium nitrate, barium nitrate, zinc nitrate; examples of suitable alkylamine nitrates include methylamine nitrate, ethylamine nitrate, and propylamine nitrate; examples of suitable alkanolamine nitrates include ethanolamine nitrate, propanolamine nitrate, and isopropanolamine nitrate; examples of suitable chlorates include sodium chlorate, potassium chlorate, calcium chlorate, and lithium chlorate; examples of suitable perchlorates include ammonium perchlorate which is preferred for greatest sensitivity, sodium perchlorate, calcium perchlorate, potassium perchlorate, lithium perchlorate, magnesium perchlorate, barium perchlorate, and zinc perchlorate.

The detonation sensitizer is an inorganic metal compound of atomic number 13 or greater other than groups la and [la of the periodic table and other than dioxides. The detonation sensitizer is preferably a compound of copper, zinc, iron, or chromium as they produce greatest sensitivity. Compounds of aluminum, manganese, cobalt, nickel, lead, silver and mercury are also suitable. For the purpose of this invention, silicon and arsenic are not considered to be metals. Nitrates, halides, chromates, dichromates, and sulfates are preferred for their sensitivity and solubility. Oxides may also be used but oxides are not as convenient as the other compounds because of their low solubility. Mixtures of various detonation sensitizers are also contemplated. If the detonation sensitizer is also an oxidizer, it is calculated as an oxidizer for the purpose of determining if the total amount of oxidizer present falls within the percentage ranges given for this invention.

The emulsifier is a water-in-oi] emulsifier. Examples include emulsifiers derivable from sorbitol by esterification with removal of one molecule of water such as sorbitan fatty acid esters, for example, sorbitan monolaurate, sorbitan monooleate, sorbitan monopalmitate, sorbitan monostearate, and sorbitan tristearate. The monoand diglycerides of fat-forming fatty acids are also useful. Further examples include polyoxyethylene sorbitol esters such as the polyoxyethylene sorbitol beeswax derivative materials and polyoxyethylene (4) lauryl ether, polyoxyethylene(2)-ether, polyoxyethylene(2)stearyl ether, polyoxyalkylene oleyl/laurate, oleyl acid phosphate, substituted oxazolines and phosphate esters. Mixtures of various emulsifiers may also be used.

The gas may be in the form of occluded air or in a gas-entrapping material such as, for example, phenolformaldehyde or urea-formaldehyde hollow microspheres, expanded perlite, or hollow glass microspheres; if a combustible gas-entrapping material is used, it should be included as an auxiliary fuel for calculation purposes.

The compositions of this invention are preferably prepared by making a premix of the water, the inorganic oxidizer, and the detonation sensitizer and a second premix of the carbonaceous fuel and the emulsifier. The two premixes are heated, the first until the salts are in solution (about l20-205 F.) and the second until the carbonaceous fuel has liquified (about l20 F. or more). They are then blended together and emulsified which incorporates occluded air into the composition (or gasentrapping material is added at this point). Further details of the preparation of emulsion blasting agents may be obtained from Bluhm US.

Pat. No. 3,447,978 which is herein incorporated by reference.

The following compositions were prepared by making a premix of the water, the inorganic oxidizer, and the detonation sensitizer at 160 F. and a second premix of the carbonaceous fuel and the emulsifier at F. The first premix was then slowly added to the second premix with vigorous agitation to obtain a water-in-oil emulsion. The agitation was continued with cooling to occlude air (or air-entrapping material was dispersed) into the emulsion. The compositions were then extruded or tamped into high-density polyethylene tubes which were sealed with plastic caps and detonated.

The tables below give the compositions and the diameter and cap size with which they were detonated. Water of hydration is included as water and not as part of the detonation sensitizer. The density is the density when made except for compositions 6 and 20 where it is the density when detonated; these two compositions were detonated in 4-inch diameter cartridges in order that the velocity and detonation pressure could be determined. Velocity was determined by the electronic counter method in 1-inch diameter or greater and detonation pressure by the Aquarium method in 4- inch diameter. Examples 26, 27, and 44 are preferred, example 26 because ofits storage stability and low temperature sensitivity and examples 27 and 44 because they are almost as good as examples 26 but are more economical.

TABLE I Compositions Ingredients 1 2 Velocity (i.p.s.).. Pressure (kilobars Diameter (inch paraffin, mineral, animal, and petroleum oils, and vegetable oils; bv about 55 to about 87 percent of an oxidizer comprising about 20 to about 95 percent ammonium nitrate, about to about 40 percent of an other inorganic nitrate, up to about 60 percent ethylene diamine dinitrate, up to about 40 percent alkylamine nitrate or alkanolamine nitrate, and up to about 30 percent inorganic chlorate or perchlorate;

c. about 10 to about 25 percent water;

d. about one-half to about 2 percent water-in-oil emulsifier;

e. sufficient occluded gas or gas-entrapping material to give the composition a density of about 0.9 to about 1.40 gms./cc.; and

f. about 0.1 to about percent of a detonation sensitizer comprising a water-soluble oxide, nitrate, halide, chromate, dichromate, and sulfate compound in which said compound contains a metal selected from the group consisting of aluminum, manganese, cobalt, nickel, lead, silver, mercury, copper, zinc, iron, and chromium.

2. The composition of claim 1 wherein said other inorganic nitrate is sodium nitrate.

3. The composition of claim 1 wherein said oxidizer comprises about 55 to about 80 percent ammonium nitrate, about 5 to about 15 percent sodium nitrate, about 10 to about 35 percent ethylene diamine dinitrate, and about 5 to about 10 percent ammonium perchlorate.

4. The composition of claim 1 wherein up to about 10 percent of an auxiliary fuel is included.

5. The composition of claim 4 wherein said auxiliary fuel is aluminum or sulfur.

6. The composition of claim 1 wherein about 0.25 to about 2.0 percent of a gelling agent is included.

7. The composition of claim 6 wherein said gelling agent is guar gum.

8. A cap-sensitive water-in-oil emulsion explosive composition comprising:

a. about 2 to about 6 percent water-immiscible,

emulsifiable fuel which is liquifiable at a temperature between about 110 F, and about 160 F., selected from the group consisting of petrolatum,

insect waxes,

microcrystalline, paraffin, mineral, animal. and in sect waxes, petroleum oils, and vegetable oils;

b. about to about percent of an oxidizer comprising about 20 to about percent ammonium nitrate, about 5 to about 40 percent of an other inorganic nitrate, up to about 60 percent ethylene diamine dinitrate, up to about 40 percent alkylamine nitrate or alkanolamine nitrate, and up to about 30 percent inorganic chlorate or perchlorate;

c. about 15 to about 20 percent water;

(1. about three-fourths to l percent emulsifier;

e. sufficient occluded gas or gas-entrapping material to give the composition a density of about L05 to about 1.25 gms./cc.; and

f. about 2 to about 6 percent of a detonation sensitizer comprising a water-soluble oxide, nitrate, halide, chromate, dichromate, and sulfate compound in which said compound contains a metal selected from the group consisting of aluminum, manganese, cobalt, nickel, lead, silver, mercury, copper, zinc, iron, and chromium.

9. The composition of claim 8 wherein said oxidizer comprises. about 55 to about 80 percent ammonium nitrate, about 5 to about 15 percent sodium nitrate, about 10 to about 35 percent ethylene diamine dinitrate, and about 5 to about 10 percent ammonium perchlorate.

10. The composition of claim 8 wherein said gas is in the form of occluded air bubbles.

11. The composition of claim 8 wherein said gas is in a gas-entrapping material.

12. The composition of claim 8 wherein said composition includes up to about 10 percent auxiliary fuel.

13. The composition of claim 12 wherein said auxiliary fuel is aluminum or sulfur.

14. The composition of claim 13 wherein about 0.25 percent to about 2.0 percent of a gelling agent is included.

15. The composition of claim 14 wherein said gelling agent is guar gum.

16. A composition of claim 1 wherein said gas-entrapping material is selected from the group consisting of expanded perlite and hollow microspheres of phenol-formaldehyde, urea-formaldehyde, and glass.

mirth STATES PATENT WPHCE CETlPlCATE 0P CORPTECTTN Patent No. 3,715 Dated February 6 1973 Inventor s Charles G. Wade It is certified that error appears in the aboveidentified patent and that said Letters Patent are hereby corrected as shown below:

Table I, line 22, entitled "Velocity (f.p.s.)", the figure "19,550" shouldbe centered directly under Composition "6".

Table l line 23 entitled "Pressure -(kil obars)", the figure "120" should be centered directly under Composition "6".

Table II, line 21, entitled "Velocity -(f.p.s.)", the figure "16,000" should be centered directly under Compos ition "l9" and the figure "18,748" should be centered directly under Composition "20;"

Table II, line 22, entitled "Pressure (kilobars)", the figure "84" should be centered directly under Composition "20".

Table III, Line 28, entitled "Velocity (f.p.s.)", the figure "16,000" should be centered directly under Composition "29".

Signed and sealed this 10th day of July 1973 (SEAL) Attest:

EDWARD MTLETQHLR JR. RENE TEGTMEVEK Attesting Officer Acting Commissioner of Patents UNTTEB d'iATES PATENT errrcr CERTTWCATE 0i CQRTFECTWN Patent No. 3 715 247 Dated February 6 197 3 Invento' -(s) Charles G. Wade It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Table I, line 22, entitled "Velocity (f.p.s.)", the figure "19,550" should'be centered directly under Composition "6".

Table I, line 23, entitled "Pressure -(1 il obars)", the figure "120" should be centered directly under Composition 6".

Table T1, line 21, entitled "Velocity -(f.p.s.)"', the figure l6,000" should be centered directly under Composition "l9" and the figure "18,748" should be centered directly under Composition "20;"

Table II, line 22, entitled "Pressure [kilobars)", the figure "84" should be centered directly under Composition "20''.

Table III, Line 28, entitled "Velocity (f.p.s.)", the figure "16,000" should be centered directly under Composition "29".

Signed and sealed this 10th day of July 1973 (SEAL) Attest:

RENE TEGTMEYER Attesting Officer I 

1. A cap-sensitive water-in-oil emulsion explosive composition comprising: a. about 1 to about 10 percent of a water-immiscible, emulsifiable carbonaceous fuel liquifiable at a temperature up to about 200* F., selected from the group consisting of petrolatum, microcrystalline, paraffin, mineral, animal, and insect waxes, petroleum oils, and vegetable oils; b. about 55 to about 87 percent of an oxidizer comprising about 20 to about 95 percent ammonium nitrate, about 5 to about 40 percent of an other inorganic nitrate, up to about 60 percent ethylene diamine dinitrate, up to about 40 percent alkylamine nitrate or alkanolamine nitrate, and up to about 30 percent inorganic chlorate or perchlorate; c. about 10 to about 25 percent water; d. about one-half to about 2 percent water-in-oil emulsifier; e. sufficient occluded gas or gas-entrapping material to give the composition a density of about 0.9 to about 1.40 gms./cc.; and f. about 0.1 to about 15 percent of a detonation sensitizer comprising a water-soluble oxide, nitrate, halide, chromate, dichromate, and sulfate compound in which said compound contains a metal selected from the group consisting of aluminum, manganese, cobalt, nickel, lead, silver, mercury, copper, zinc, iron, and chromium.
 2. The composition of claim 1 wherein said other inorganic nitrate is sodium nitrate.
 3. The composition of claim 1 wherein said oxidizer comprises about 55 to about 80 percent ammonium nitrate, about 5 to about 15 percent sodium nitrate, about 10 to about 35 percent ethylene diamine dinitrate, and about 5 to about 10 percent ammonium perchlorate.
 4. The composition of claim 1 wherein up to about 10 percent of an auxiliary fuel is included.
 5. The composition of claim 4 wherein said auxiliary fuel is aluminum or sulfur.
 6. The composition of claim 1 wherein about 0.25 to about 2.0 percent of a gelling agent is included.
 7. The composition of claim 6 wherein said gelling agent is guar gum.
 8. A cap-sensitive water-in-oil emulsion explosive composition comprising: a. about 2 to about 6 percent water-immiscible, emulsifiable fuel which is liquifiable at a temperature between about 110* F. and about 160* F., selected from the group consisting of petrolatum, microcrystalline, paraffin, mineral, animal, and insect waxes, petroleum oils, and vegetable oils; b. about 75 to about 85 percent of an oxidizer comprising about 20 to about 95 percent ammonium nitrate, about 5 to about 40 percent of an other inorganic nitrate, up to about 60 percent ethylene diamine dinitrate, up to about 40 percent alkylamine nitrate or alkanolamine nitrate, and up to about 30 percent inorganic chlorate or perchlorate; c. about 15 to about 20 percent water; d. about three-fourths to 1 1/4 percent emulsifier; e. sufficient occluded gas or gas-entrapping material to give the composition a density of about 1.05 to about 1.25 gms./cc.; and f. about 2 to about 6 percent of a detonation sensitizer comprising a water-soluble oxide, nitrate, halide, chromate, dichromate, and sulfate compound in which said compound contains a metal selected from the group consisting of aluminum, manganese, cobalt, nickel, lead, silver, mercury, copper, zinc, iron, and chromium.
 9. The composition of claim 8 wherein said oxidizer comprises about 55 to about 80 percent ammonium nitrate, about 5 to about 15 percent sodium nitrate, about 10 to about 35 percent ethylene diamine dinitrate, and about 5 to about 10 percent ammonium perchlorate.
 10. The composition of claim 8 wherein said gas is in the form of occluded air bubbles.
 11. The composition of claim 8 wherein said gas is in a gas-entrapping material.
 12. The composition of claim 8 wherein said composition includes up to about 10 percent auxiliary fuel.
 13. The composition of claim 12 wherein said auxiliary fuel is aluminum or sulfur.
 14. The composition of claim 13 wherein about 0.25 percent to about 2.0 percent of a gelling agent is included.
 15. The composition of claim 14 wherein said gelling agent is guar gum. 